Population-Based Epidemiology of Autoimmune Seizures and Epilepsies.

OBJECTIVE

To estimate the prevalence, incidence, and disease burden of autoimmune seizures and epilepsies in Olmsted County.

METHODS

We conducted a retrospective, population-based study using the Rochester Epidemiology Project (1996-2019). Age- and sex-standardized rates (2019 United States standard population) per 100,000 were calculated with 95% confidence intervals (95% CIs). Temporal trends in incidence were assessed over 3 consecutive 8-year intervals (1996-2003, 2004-2011, and 2012-2019) using Poisson regression to estimate rate ratios per period and trend. Disability-adjusted life years (DALYs), years of life lost (YLL), and years lived with disability (YLD) and 95% uncertainty intervals (95% UIs) were estimated for 2019.

RESULTS

Twenty-three patients were identified between 1996 and 2019. In 2019, the standardized prevalence of all autoimmune seizures and epilepsies was 9.81 (95% CI, 5.59-15.21) per 100,000, including autoimmune-associated epilepsy (AAE) 7.27 (3.74-11.95) and acute symptomatic seizures secondary to autoimmune encephalitis (ASSAE) 2.55 (0.69-5.60). From 1996 to 2019, the standardized incidence was 0.50 (0.29-0.77) per 100,000 person-years overall, with AAE 0.36 (0.19-0.59) and ASSAE 0.15 (0.05-0.30). By period, the standardized incidence of all autoimmune seizures and epilepsies suggested a rising trend from 0.28 (95% CI, 0.06-0.68) in 1996 to 2003 to 0.60 (95% CI, 0.24-1.12) in 2004-2011, then plateaued at 0.53 (95% CI, 0.21-1.00) in 2012 to 2019 (rate ratio per 8-year interval 1.30, 95% CI, 0.71-2.38), largely driven by the seropositive subgroup. The standardized DALY rate was 26.27 (95% Uncertainly intervals [UI], 5.30-67.09) per 100,000 (YLL 20.07 [0.00-60.21] and YLD 6.20 [5.06-7.39]).

INTERPRETATION: Although autoimmune seizures and epilepsies remain rare, they result in a disproportionately high disease burden. ANN NEUROL 2026;100:74-83.